Identity-Based Key Generation Without Trusted Key Escrow
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Solution Overview
Problem
Identity-based encryption (IBE) systems rely on a trusted third party (TTP) to generate a user's private key from a master private key, which compromises the security as the TTP can decrypt messages encrypted with the user's public key.
Innovation Solution
A method for generating an identity-based cryptographic key, wherein the user is at least partially responsible for generating their own private key, which involves the use of a set of private key shares and public key shares, with each key-generating party only knowing a part of the private key, and the user combining these shares to generate their own private key, and storing the identity-based public key on a blockchain for validation and revocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a trusted third party generates the user's private key from a master private key and the user's identity, then the private key can be generated securely, but the trusted third party gains knowledge of the user's private key and can decrypt messages
Solution Approach 1:
The private key is segmented into multiple key shares distributed among multiple trusted parties. Each party holds only a portion of the key material, and no single party can reconstruct the full private key or decrypt messages alone. This segmentation eliminates the single point of failure and privacy compromise associated with a single trusted third party.
Solution Approach 2:
A cryptographic mediator (such as a threshold decryption protocol or multi-party computation mechanism) is introduced to enable secure key generation and decryption operations. The mediator coordinates between multiple trusted parties without any single party having access to the complete private key, thus maintaining security while enabling collaborative cryptographic operations.
2Adaptability or versatility
If a trusted third party maintains knowledge of all private keys for key management and revocation, then key revocation can be performed, but the system becomes centralized and the third party can access all encrypted communications
Solution Approach 1:
The key management function is segmented across multiple independent parties rather than centralized in a single trusted third party. Each party manages their own key share independently, and revocation operations require coordination among multiple parties, distributing both the capability and the complexity across the system.
Solution Approach 2:
The system performs preliminary actions by pre-distributing key shares and establishing threshold decryption mechanisms before any communication occurs. This preliminary setup enables future revocation operations to be performed by a predetermined subset of parties without requiring a centralized authority, thus enabling adaptability while reducing centralized complexity.
3Reliability
If multiple key-generating parties each generate their own private key shares, then no single party has complete knowledge of the private key, but the key generation process becomes more complex
Solution Approach 1:
Each key-generating party independently generates their own private key share using their own secret inputs and the user's identity, without requiring coordination with other parties during the key generation process. This self-service approach maintains distributed security while minimizing the complexity of multi-party coordination, as each party operates autonomously to contribute their share to the collective key structure.
Data Source
AI summary
A computer-implemented method for generating an identity-based cryptographic key, the method comprising: obtaining a set of private key shares and a set of corresponding public key shares, wherein each private key share is generated based on the personal identifier, and wherein at least one of the set of private key shares is generated by a respective one of a set of key-generating parties; generating an identity-based private key based on each of the one or more private key shares; and generating a partial identity-based public key, wherein the partial identity-based public key is generated based on each of the set of corresponding public key shares; transmitting the partial identity-based public key to at least one of the set of key-generating parties for generating the identity-based public key; and/or generating the identity-based public key, wherein the identity-based public key comprises the personal identifier and the partial identity-based public key.